Polyacenes are polymers predicted to show industrially important properties including non-linear optics and high-temperature superconductivity, see references 1. Unfortunately, confirmation of the predicted properties has not yet been performed due to the lack of an efficient method to prepare polyacenes.
Cyclobutabenzenes, especially the 7,8-dibromo derivatives 2 (depicted in scheme 1), are valuable synthons for functionalized ortho-quiodimethanes that can be trapped by Diels-Alder reactions. The product of such a reaction is a tetrahydronaphtalene 4 derivative having two cis bromine atoms in the 1 and 4 positions. If the dienophile has two cis hydrogen atoms, and since the Diels-Alder addition is completely endo, these hydrogen atoms end the reaction antiperiplanar to the bromine atoms. Such an orientation facilitates elimination of two HBr molecules to form the corresponding naphtalenic system 6 as described in reference 2 and depicted in scheme 1:

Reference 4 discloses the Diels-Alder condensation of 7,8,9,10-tetrabromo-[1,2][4,5] bicyclobutabenzene 16 with tetracyanoethylene 18, scheme 2:

Reference 4 further discloses the Diels-Alder condensation of two equivalents of 7,8-dibromo cyclobutabenzene 2 with one equivalent of 1,4-benzoquinone 12 to form the bis-adduct that eliminates four equivalents of HBr to form the pentacyclic quinone 14, scheme 3:

Thus, it is expected that of 7,8,9,10-tetrabromo-[1,2][4,5] bicyclobutabenzene 16 can react with benzoquinone 12, in analogy to schemes 2 and 3, to form polyquinone 20, scheme 4:

As further seen in scheme 4, subsequent reduction of polyquinone 20 is expected to yield polyacene 22.
As the use of non-brominated bicyclobutabenzene would result in two saturated centers between the aromatic and quinone moieties, deconjugating the polyacene 20, to synthesize polyquinone 20 it is necessary to use the brominated bicyclobutabenzene, compound 16 or any of the four all-trans tetrabromo isomers thereof. For the Diels-Alder condensation to take place, two bromine atoms on a cyclobutane ring must be in a trans orientation.
A number of methods for synthesizing compound 16 or any of the four all-trans bromo isomers thereof have been disclosed. Reference 5 discloses a synthesis of compound 16 using iodide-mediated ring closure and reports a 2% yield. Reference 4 describes a synthesis of compound 16 using stochiometric amounts of (Bu3P)2Ni(COD) and reports a 10% yield.
The bottleneck of the above-proposed route of synthesizing polyacenes such as 22 is the preparation of compounds such as 16. The known methods of synthesizing compound such as 16 suffer from low yields.
It would be highly advantageous to have a high-yield synthesis for (trans dibromocyclobuta) aromatic compounds such as 16.